| Heat-resistant coating high temperature resistance, low heat conductivity, andinstantaneous burns resistance. With the developments of aeronautics and astronautics, greatprogress has been made in the studies on the heat-resistant coating. The heat-resistant coatinghas been one of the most important heat-resistant materials increasingly. When an aeroplanetakes off, lies in normal operation or launches missiles, it will be situated in variedaerodynamic heating environments, which will endamage the specific materials in theaeroplane down to different degree. The heat-resistant material is mainly used to protect thestructural materials from aerodynamic heating.Silicone resin has special structure, in which the silicone oxygen bond has high bondenergy, the silicone carbon bond can form the dπ-pπ coordination bond, the silicone substituentsuch as methyl or phenyl has the shielding effect, which could protect the silicone oxygenfrom the attack of impurities. Therefore the silicone resin has the excellent heat stability, andcome into being one of the preferred materials in making heat-resistant coating. The siliconeincluding Si-bonded methyl group and phenyl group (methyl phenyl silicone resin for short)holds the chief place in the silicone resin field because of its high thermal-oxidative stability,good toughness in high temperature and good compatibility with other fillers and resins.The compositions, structures and properties of several methyl phenyl silicone resins havebeen studied in detail. K -9-0, K -2104, 137-248 resins produced by Russia, DC-805, 840,806A from America, GJT-724, 743 from the Organic silicone center of Cheng du, 6405 resinfrom France and Resin 12#, 14#, 16# made in our lab have been covered in this paper. The cureagent, catalyst and the curing method of silicone resin have been studied in detail, includingthe mechanics and heat resistance. The heat-resistant coating, the mating priming coat andfinishing coat have been prepared successfully from the resins containing Resin 16#, K -9-0/ K -2104/l37-248, Dc-805/840 respectively.DC-805, 840, 806A have excellent heat stability, and the value of R/Si is from 1.4 to 1.6,the proportion of phenyl to methyl is from 1.1 to 1.2. The blends of such three resins, whichhave the proper proportion of each resin, have the uniform properties of hardness andtoughness. Both 6405 resin and GJT-724 resin are hard resins and brittle after curing. Theycouldn't get into use in the heat-resistant coating by oneself without the flexibilizer, thoughthey have excellent heat resistance.According to the experimental results, the silicone resin could be cured under the 90℃,especially in the room temperature with a cure agent which is a kind of silicone nitrogenpolymer. The tin carboxylate can accelerate the curing reaction. The strength and heatresistance of cured resin depends on the curing temperature and time tO some degree.The coating is prepared in a conventional manneF, usually by spray. The expIoring studieshave been carried out about the heat-resistant coating prepared in our lab, such as how to treatthe filler, how to evaluatC the heat properties of coating and how to gst the effect of filler andresin on the coating. The heat stability and the microcosmic aPpearances of the coating havebeen analyzed in detail in this paPeL The coating prepared in our lab has synthetic propertiescompared with other coating used in the same field. |
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